Plumbogummite mineral. Plumbogummite is a rare mineral, a lead-aluminium phosphate (Pb.Al3.(PO4)2.(OH).5[H2O]). A member of the alunite-crandallite group, it occurs in an amorphous to sub-crystalline botryoidal habitat, with colours varying from blue (as here) to grey, yellow or greenish. The dispersed green crystals in this specimen are of mimetite. This sample, from China's Guangxi Province, is 22 centimetres across.